1. Field of the Invention
This invention relates to exercise equipment used to rehabilitate and strengthen a patient's upper extremity, and particularly to a form of exercise equipment for use by stroke or hemiplegic patients to reduce muscle tension and spasms in the shoulder, elbow and wrist muscle groups.
2. Discussion of the Related Art
One of the more common problems of a stroke is the decreased function of the upper extremity. A severe stroke will usually make one of the victim's arms nonfunctional. The arm moves through stages of recovery that range from completely flaccid, to spastic, to possible return of normal function. A large number of stroke victims have some form of spasticity that affects their ability to use their arm. When muscles become spastic, they are tighter than a normal muscle. Imagine tensing one's bicep to hold a ten pound weight. Such tension exists all the time in a spastic muscle. The involved muscles are receiving messages from the damaged brain that tell them to contract. There are varying levels of spasticity that range from mild to severe.
Spastic muscles are shortened muscles and need to be forcefully extended frequently to prevent permanent deformity. One of the most common postures created by spastic muscles of a stroke victim is a flexor synergy. In the upper extremity, this posture can be easily seen as internal rotation of the shoulder, adduction of the arm, flexion of the elbow, pronation of the forearm, flexion of the wrist, ulnar deviation of the wrist, and flexion of the fingers. With severe spasticity this posture will surely become somewhat permanent as shortened muscles lose their ability to stretch and become permanently fixed in the contracted position. The fixed, shortened muscle forms what is commonly called a contracture. A contracture can be most easily recognized by the fixed nature of the joints of the involved extremity. The only way to prevent formation of a contracture is through a consistent stretching program and aggressive positioning of the affected arm. When stretching and positioning are ignored, range of motion becomes very limited and cannot be increased effectively once the contracture has formed. With severe spasticity, even a conscientious program of stretching and positioning cannot prevent some level of contracture and deformity of the arm. Fortunately, not all stroke victims have severe spasticity. In fact, many stroke victims move through stages of flaccidity to spasticity to normal function.
Throughout recent history there have been numerous devices for use in exercising and rehabilitation of a stroke patient's shoulder, elbow and wrist muscles. Therapists typically give patients "cane exercises" (FIG. 1), where the patient holds the cane or bar with their hands wrapped around the longitudinal axis of the cane. Placement of the hands in this manner affects the shoulder position by rotating the humerus and greater tuberosity inwardly, increasing the possibility of the greater tuberosity impinging upon the shoulder during the exercise and producing a painful disabling shoulder condition. Placing the hands in a position perpendicular to the longitudinal axis of the cane rotates the humerus and greater tuberosity outwardly as desired for shoulder flexion and shoulder abduction exercises. Schneider, Kennedy, and Plant, in their book entitled, "Sports Injuries: Mechanisms, Prevention, and Treatment" describe impingement injuries to the rotator cuff and emphasize the need for a shoulder strengthening program that focuses on the rotator cuff muscles. These exercises are done with the elbow close to the side, externally rotating and internally rotating the shoulder against resistance. Stretching exercises to regain full range of motion are also very necessary. There is a need for a shoulder exercise device that maintains proper shoulder position, has multiple handles for varied arm spread, is light and relatively compact, and is affordable for clinic and home use.
U.S. Pat. No. 4,664,370 describes the use of a flat metal bar with a complicated handle mechanism for use in exercising a person's wrists, arms and upper body. Changing the working length of the device requires the unfastening of wing nuts and physically repositioning the handles by detaching and reattaching them. The length of the flat longitudinal bar is described as approximately the width of a person's shoulders, but since it is made of a single piece of flat stock, cannot adjust to accommodate patient's of different shoulder widths. In addition, the bar is made from aluminum or steel which presents a serious hazard to patients who sometimes have great difficulty controlling their movements. The hazard is accentuated by the angular nature of the bar's edges, and protruding wing nuts.
U.S. Pat. No. 4,513,963 teaches the use of a similar device that incorporates weights and has a protective covering. The patent does not teach, however, the use of multiple handles to provide flexibility of arm spread and specific hand orientation for the user. Using the weights incorporated in the handles would not be suitable for substantially all of the rehabilitation population targeted by the present invention.